Faria joined the side two years ago after Jose Mourinho was appointed as manager and the two have worked together for more than 17 years.

"After a lot of consideration, and with a very heavy heart, I have decided the time is right for me to move on," said the 42-year-old Portuguese.

Mourinho added: "The intelligent student is now a football expert, ready for a successful career as a manager."

Mourinho said of the pair's career-long association: "17 years… in Leiria, Porto, London, Milan, Madrid, London again and Manchester. Training, playing, travelling, studying, laughing and also a few tears of happiness.

"17 years and the kid is now a man.

"I will miss my friend and that is the hardest thing for me, but his happiness is more important and, of course, I respect his decision, especially because I know that we will always be together.

"Be happy, brother."

Faria, who will leave at the end of the season, added: "I have had 17 years of incredible and unforgettable experiences.

"However, I have felt for some time that I would like to spend much more quality time with my family before pursuing any new challenge in my professional life.

"My heartfelt thanks go to the manager, Jose Mourinho, for the belief he had in me, all those years ago, when it all was just a student dream."

United, second in the Premier League, play Watford at Old Trafford on Sunday before facing Chelsea in the FA Cup final on 19 May.